The Experts below are selected from a list of 318 Experts worldwide ranked by ideXlab platform
Jun Lin - One of the best experts on this subject based on the ideXlab platform.
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controllable red green blue rgb and bright white upconversion luminescence of lu2o3 yb3 er3 tm3 nanocrystals through single Laser Excitation at 980 nm
Chemistry: A European Journal, 2009Co-Authors: Jun Yang, Cuimiao Zhang, Chong Peng, Lili Wang, Ruitao Chai, Jun LinAbstract:Lu2O3:Yb3+/Er3+/Tm3+ nanocrystals have been successfully synthesized by a solvothermal process followed by a subsequent heat treatment at 800 degrees C. Powder X-ray diffraction, transmission electron microscopy, upconversion photoluminescence spectra, and kinetic decay were used to characterize the samples. Under single-wavelength diode Laser Excitation of 980 nm, the bright blue emissions of Lu2O3:Yb3+, Tm3+ nanocrystals near 477 and 490 nm were observed due to the (1)G(4)-> H-3(6) transition of Tm3+. The bright green UC emissions of Lu2O3:Er3+ nanocrystals appeared near 540 and 565 nm were observed and assigned to the H-2(11/2)-> I-4(15/2) and S-4(3/2)-> I-4(15/2) transitions, respectively, of Er3+. The ratio of the intensity of green luminescence to that of red luminescence decreases with an increase of concentration of Yb3+ in Lu2O3:Er3+ nanocrystals.
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controllable red green blue rgb and bright white upconversion luminescence of lu2o3 yb3 er3 tm3 nanocrystals through single Laser Excitation at 980 nm
Chemistry: A European Journal, 2009Co-Authors: Jun Yang, Cuimiao Zhang, Chong Peng, Lili Wang, Ruitao Chai, Jun LinAbstract:Light fantastic! Lu(2)O(3):Yb(3+)/Er(3+)/Tm(3+) nanocrystals with controllable red, green, blue (RGB) and bright white upconversion luminescence by a single Laser Excitation of 980 nm have been successfully synthesized (see picture). Due to abundant UC PL colors, it can potentially be used as fluorophores in the field of color displays, back light, UC Lasers, photonics, and biomedicine.Lu(2)O(3):Yb(3+)/Er(3+)/Tm(3+) nanocrystals have been successfully synthesized by a solvothermal process followed by a subsequent heat treatment at 800 degrees C. Powder X-ray diffraction, transmission electron microscopy, upconversion photoluminescence spectra, and kinetic decay were used to characterize the samples. Under single-wavelength diode Laser Excitation of 980 nm, the bright blue emissions of Lu(2)O(3):Yb(3+), Tm(3+) nanocrystals near 477 and 490 nm were observed due to the (1)G(4)-->(3)H(6) transition of Tm(3+). The bright green UC emissions of Lu(2)O(3):Er(3+) nanocrystals appeared near 540 and 565 nm were observed and assigned to the (2)H(11/2)-->(4)I(15/2) and (4)S(3/2)-->(4)I(15/2) transitions, respectively, of Er(3+). The ratio of the intensity of green luminescence to that of red luminescence decreases with an increase of concentration of Yb(3+) in Lu(2)O(3):Er(3+) nanocrystals. In sufficient quantities of Yb(3+) with resprct to Er(3+), the bright red UC emission of Lu(2)O(3):Yb(3+)/Er(3+) centered at 662 nm was predominant, due to the (4)F(9/2)-->(4)I(15/2) transition of Er(3+). Based on the generation of red, green, and blue emissions in the different doped Lu(2)O(3):RE(3+) nanocrystals, it is possible to produce the luminescence with a wide spectrum of colors, including white, by the appropriate doping of Yb(3+), Tm(3+), and Er(3+) in the present Lu(2)O(3) nanocrystals. Namely, Lu(2)O(3):3 %Yb(3+)/0.2 %Tm(3+)/0.4 %Er(3+) nanocrystals show suitable intensities of blue, green, and red (RGB) emission, resulting in the production of perfect and bright white light with CIE-x=0.3456 and CIE-y=0.3179, which is very close to the standard equal energy white light illuminate (x=0.33, y=0.33). Because of abundant luminescent colors from RGB to white in Lu(2)O(3):Yb(3+)/Er(3+)/Tm(3+) nanocrystals under 980 nm Laser diode (LD) Excitation, they can potentially be used as fluorophores in the field of color displays, back light, UC Lasers, photonics, and biomedicine.
Shimon Weiss - One of the best experts on this subject based on the ideXlab platform.
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three color alternating Laser Excitation of single molecules monitoring multiple interactions and distances
Biophysical Journal, 2007Co-Authors: Nam Ki Lee, Achillefs N Kapanidis, Hye Ran Koh, Seong Keun Kim, You Korlann, Younggyu Kim, Natalie R Gassman, Shimon WeissAbstract:We introduce three-color alternating-Laser Excitation (3c-ALEX), a fluorescence resonance energy transfer (FRET) method that measures up to three intramolecular distances and complex interaction stoichiometries of single molecules in solution. This tool extends substantially the capabilities of two-color ALEX, which employs two alternating Lasers to study molecular interactions (through probe stoichiometry S) and intramolecular distances (through FRET efficiency E), and sorts fluorescent molecules in multi-dimensional probe-stoichiometry and FRET-efficiency histograms. Probe-stoichiometry histograms allowed analytical sorting, identification, and selection of diffusing species; selected molecules were subsequently represented in FRET-efficiency histograms, generating up to three intramolecular distances. Using triply labeled DNAs, we established that 3c-ALEX enables 1), FRET-independent analysis of three-component interactions; 2), observation and sorting of singly, doubly, and triply labeled molecules simultaneously present in solution; 3), measurements of three intramolecular distances within single molecules from a single measurement; and 4), dissection of conformational heterogeneity with improved resolution compared to conventional single-molecule FRET. We also used 3c-ALEX to study large biomolecules such as RNA polymerase-DNA transcription complexes, and monitor the downstream translocation of RNA polymerase on DNA from two perspectives within the complex. This study paves the way for advanced single-molecule analysis of complex mixtures and biomolecular machinery.
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alternating Laser Excitation of single molecules
Accounts of Chemical Research, 2005Co-Authors: Achillefs N Kapanidis, Ted A Laurence, Nam Ki Lee, Emmanuel Margeat, Xiangxu Kong, Shimon WeissAbstract:Single-molecule fluorescence spectroscopy addresses biological mechanisms and enables ultrasensitive diagnostics. We describe a new family of single-molecule fluorescence methods that uses alternating-Laser Excitation (ALEX) of diffusing or immobilized biomolecules to study their structure, interactions, and dynamics. This is accomplished using ratios that report on the distance between and the stoichiometry of fluorophores attached to the molecules of interest. The principle of alternation is compatible with several time scales, allowing monitoring of fast dynamics or simultaneous monitoring of a large number of individual molecules.
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accurate fret measurements within single diffusing biomolecules using alternating Laser Excitation
Biophysical Journal, 2005Co-Authors: Nam Ki Lee, Achillefs N Kapanidis, You Wang, Xavier Michalet, Jayanta Mukhopadhyay, Richard H Ebright, Shimon WeissAbstract:Fluorescence resonance energy transfer (FRET) between a donor (D) and an acceptor (A) at the single-molecule level currently provides qualitative information about distance, and quantitative information about kinetics of distance changes. Here, we used the sorting ability of confocal microscopy equipped with alternating-Laser Excitation (ALEX) to measure accurate FRET efficiencies and distances from single molecules, using corrections that account for cross-talk terms that contaminate the FRET-induced signal, and for differences in the detection efficiency and quantum yield of the probes. ALEX yields accurate FRET independent of instrumental factors, such as Excitation intensity or detector alignment. Using DNA fragments, we showed that ALEX-based distances agree well with predictions from a cylindrical model of DNA; ALEX-based distances fit better to theory than distances obtained at the ensemble level. Distance measurements within transcription complexes agreed well with ensemble-FRET measurements, and with structural models based on ensemble-FRET and x-ray crystallography. ALEX can benefit structural analysis of biomolecules, especially when such molecules are inaccessible to conventional structural methods due to heterogeneity or transient nature.
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fluorescence aided molecule sorting analysis of structure and interactions by alternating Laser Excitation of single molecules
Proceedings of the National Academy of Sciences of the United States of America, 2004Co-Authors: Achillefs N Kapanidis, Ted A Laurence, Emmanuel Margeat, Soren Doose, Shimon WeissAbstract:We use alternating-Laser Excitation to achieve fluorescence-aided molecule sorting (FAMS) and enable simultaneous analysis of biomolecular structure and interactions at the level of single molecules. This was performed by labeling biomolecules with fluorophores that serve as donor–acceptor pairs for Forster resonance energy transfer, and by using alternating-Laser Excitation to excite directly both donors and acceptors present in single diffusing molecules. Emissions were reduced to the distance-dependent ratio E , and a distance-independent, stoichiometry-based ratio S . Histograms of E and S sorted species based on the conformation and association status of each species. S was sensitive to the stoichiometry and relative brightness of fluorophores in single molecules, observables that can monitor oligomerization and local-environment changes, respectively. FAMS permits equilibrium and kinetic analysis of macromolecule-ligand interactions; this was validated by measuring equilibrium and kinetic dissociation constants for the interaction of Escherichia coli catabolite activator protein with DNA. FAMS is a general platform for ratiometric measurements that report on structure, dynamics, stoichiometries, environment, and interactions of diffusing or immobilized molecules, thus enabling detailed mechanistic studies and ultrasensitive diagnostics.
Jun Yang - One of the best experts on this subject based on the ideXlab platform.
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controllable red green blue rgb and bright white upconversion luminescence of lu2o3 yb3 er3 tm3 nanocrystals through single Laser Excitation at 980 nm
Chemistry: A European Journal, 2009Co-Authors: Jun Yang, Cuimiao Zhang, Chong Peng, Lili Wang, Ruitao Chai, Jun LinAbstract:Lu2O3:Yb3+/Er3+/Tm3+ nanocrystals have been successfully synthesized by a solvothermal process followed by a subsequent heat treatment at 800 degrees C. Powder X-ray diffraction, transmission electron microscopy, upconversion photoluminescence spectra, and kinetic decay were used to characterize the samples. Under single-wavelength diode Laser Excitation of 980 nm, the bright blue emissions of Lu2O3:Yb3+, Tm3+ nanocrystals near 477 and 490 nm were observed due to the (1)G(4)-> H-3(6) transition of Tm3+. The bright green UC emissions of Lu2O3:Er3+ nanocrystals appeared near 540 and 565 nm were observed and assigned to the H-2(11/2)-> I-4(15/2) and S-4(3/2)-> I-4(15/2) transitions, respectively, of Er3+. The ratio of the intensity of green luminescence to that of red luminescence decreases with an increase of concentration of Yb3+ in Lu2O3:Er3+ nanocrystals.
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controllable red green blue rgb and bright white upconversion luminescence of lu2o3 yb3 er3 tm3 nanocrystals through single Laser Excitation at 980 nm
Chemistry: A European Journal, 2009Co-Authors: Jun Yang, Cuimiao Zhang, Chong Peng, Lili Wang, Ruitao Chai, Jun LinAbstract:Light fantastic! Lu(2)O(3):Yb(3+)/Er(3+)/Tm(3+) nanocrystals with controllable red, green, blue (RGB) and bright white upconversion luminescence by a single Laser Excitation of 980 nm have been successfully synthesized (see picture). Due to abundant UC PL colors, it can potentially be used as fluorophores in the field of color displays, back light, UC Lasers, photonics, and biomedicine.Lu(2)O(3):Yb(3+)/Er(3+)/Tm(3+) nanocrystals have been successfully synthesized by a solvothermal process followed by a subsequent heat treatment at 800 degrees C. Powder X-ray diffraction, transmission electron microscopy, upconversion photoluminescence spectra, and kinetic decay were used to characterize the samples. Under single-wavelength diode Laser Excitation of 980 nm, the bright blue emissions of Lu(2)O(3):Yb(3+), Tm(3+) nanocrystals near 477 and 490 nm were observed due to the (1)G(4)-->(3)H(6) transition of Tm(3+). The bright green UC emissions of Lu(2)O(3):Er(3+) nanocrystals appeared near 540 and 565 nm were observed and assigned to the (2)H(11/2)-->(4)I(15/2) and (4)S(3/2)-->(4)I(15/2) transitions, respectively, of Er(3+). The ratio of the intensity of green luminescence to that of red luminescence decreases with an increase of concentration of Yb(3+) in Lu(2)O(3):Er(3+) nanocrystals. In sufficient quantities of Yb(3+) with resprct to Er(3+), the bright red UC emission of Lu(2)O(3):Yb(3+)/Er(3+) centered at 662 nm was predominant, due to the (4)F(9/2)-->(4)I(15/2) transition of Er(3+). Based on the generation of red, green, and blue emissions in the different doped Lu(2)O(3):RE(3+) nanocrystals, it is possible to produce the luminescence with a wide spectrum of colors, including white, by the appropriate doping of Yb(3+), Tm(3+), and Er(3+) in the present Lu(2)O(3) nanocrystals. Namely, Lu(2)O(3):3 %Yb(3+)/0.2 %Tm(3+)/0.4 %Er(3+) nanocrystals show suitable intensities of blue, green, and red (RGB) emission, resulting in the production of perfect and bright white light with CIE-x=0.3456 and CIE-y=0.3179, which is very close to the standard equal energy white light illuminate (x=0.33, y=0.33). Because of abundant luminescent colors from RGB to white in Lu(2)O(3):Yb(3+)/Er(3+)/Tm(3+) nanocrystals under 980 nm Laser diode (LD) Excitation, they can potentially be used as fluorophores in the field of color displays, back light, UC Lasers, photonics, and biomedicine.
Achillefs N Kapanidis - One of the best experts on this subject based on the ideXlab platform.
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three color alternating Laser Excitation of single molecules monitoring multiple interactions and distances
Biophysical Journal, 2007Co-Authors: Nam Ki Lee, Achillefs N Kapanidis, Hye Ran Koh, Seong Keun Kim, You Korlann, Younggyu Kim, Natalie R Gassman, Shimon WeissAbstract:We introduce three-color alternating-Laser Excitation (3c-ALEX), a fluorescence resonance energy transfer (FRET) method that measures up to three intramolecular distances and complex interaction stoichiometries of single molecules in solution. This tool extends substantially the capabilities of two-color ALEX, which employs two alternating Lasers to study molecular interactions (through probe stoichiometry S) and intramolecular distances (through FRET efficiency E), and sorts fluorescent molecules in multi-dimensional probe-stoichiometry and FRET-efficiency histograms. Probe-stoichiometry histograms allowed analytical sorting, identification, and selection of diffusing species; selected molecules were subsequently represented in FRET-efficiency histograms, generating up to three intramolecular distances. Using triply labeled DNAs, we established that 3c-ALEX enables 1), FRET-independent analysis of three-component interactions; 2), observation and sorting of singly, doubly, and triply labeled molecules simultaneously present in solution; 3), measurements of three intramolecular distances within single molecules from a single measurement; and 4), dissection of conformational heterogeneity with improved resolution compared to conventional single-molecule FRET. We also used 3c-ALEX to study large biomolecules such as RNA polymerase-DNA transcription complexes, and monitor the downstream translocation of RNA polymerase on DNA from two perspectives within the complex. This study paves the way for advanced single-molecule analysis of complex mixtures and biomolecular machinery.
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alternating Laser Excitation of single molecules
Accounts of Chemical Research, 2005Co-Authors: Achillefs N Kapanidis, Ted A Laurence, Nam Ki Lee, Emmanuel Margeat, Xiangxu Kong, Shimon WeissAbstract:Single-molecule fluorescence spectroscopy addresses biological mechanisms and enables ultrasensitive diagnostics. We describe a new family of single-molecule fluorescence methods that uses alternating-Laser Excitation (ALEX) of diffusing or immobilized biomolecules to study their structure, interactions, and dynamics. This is accomplished using ratios that report on the distance between and the stoichiometry of fluorophores attached to the molecules of interest. The principle of alternation is compatible with several time scales, allowing monitoring of fast dynamics or simultaneous monitoring of a large number of individual molecules.
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accurate fret measurements within single diffusing biomolecules using alternating Laser Excitation
Biophysical Journal, 2005Co-Authors: Nam Ki Lee, Achillefs N Kapanidis, You Wang, Xavier Michalet, Jayanta Mukhopadhyay, Richard H Ebright, Shimon WeissAbstract:Fluorescence resonance energy transfer (FRET) between a donor (D) and an acceptor (A) at the single-molecule level currently provides qualitative information about distance, and quantitative information about kinetics of distance changes. Here, we used the sorting ability of confocal microscopy equipped with alternating-Laser Excitation (ALEX) to measure accurate FRET efficiencies and distances from single molecules, using corrections that account for cross-talk terms that contaminate the FRET-induced signal, and for differences in the detection efficiency and quantum yield of the probes. ALEX yields accurate FRET independent of instrumental factors, such as Excitation intensity or detector alignment. Using DNA fragments, we showed that ALEX-based distances agree well with predictions from a cylindrical model of DNA; ALEX-based distances fit better to theory than distances obtained at the ensemble level. Distance measurements within transcription complexes agreed well with ensemble-FRET measurements, and with structural models based on ensemble-FRET and x-ray crystallography. ALEX can benefit structural analysis of biomolecules, especially when such molecules are inaccessible to conventional structural methods due to heterogeneity or transient nature.
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fluorescence aided molecule sorting analysis of structure and interactions by alternating Laser Excitation of single molecules
Proceedings of the National Academy of Sciences of the United States of America, 2004Co-Authors: Achillefs N Kapanidis, Ted A Laurence, Emmanuel Margeat, Soren Doose, Shimon WeissAbstract:We use alternating-Laser Excitation to achieve fluorescence-aided molecule sorting (FAMS) and enable simultaneous analysis of biomolecular structure and interactions at the level of single molecules. This was performed by labeling biomolecules with fluorophores that serve as donor–acceptor pairs for Forster resonance energy transfer, and by using alternating-Laser Excitation to excite directly both donors and acceptors present in single diffusing molecules. Emissions were reduced to the distance-dependent ratio E , and a distance-independent, stoichiometry-based ratio S . Histograms of E and S sorted species based on the conformation and association status of each species. S was sensitive to the stoichiometry and relative brightness of fluorophores in single molecules, observables that can monitor oligomerization and local-environment changes, respectively. FAMS permits equilibrium and kinetic analysis of macromolecule-ligand interactions; this was validated by measuring equilibrium and kinetic dissociation constants for the interaction of Escherichia coli catabolite activator protein with DNA. FAMS is a general platform for ratiometric measurements that report on structure, dynamics, stoichiometries, environment, and interactions of diffusing or immobilized molecules, thus enabling detailed mechanistic studies and ultrasensitive diagnostics.
Cuimiao Zhang - One of the best experts on this subject based on the ideXlab platform.
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controllable red green blue rgb and bright white upconversion luminescence of lu2o3 yb3 er3 tm3 nanocrystals through single Laser Excitation at 980 nm
Chemistry: A European Journal, 2009Co-Authors: Jun Yang, Cuimiao Zhang, Chong Peng, Lili Wang, Ruitao Chai, Jun LinAbstract:Lu2O3:Yb3+/Er3+/Tm3+ nanocrystals have been successfully synthesized by a solvothermal process followed by a subsequent heat treatment at 800 degrees C. Powder X-ray diffraction, transmission electron microscopy, upconversion photoluminescence spectra, and kinetic decay were used to characterize the samples. Under single-wavelength diode Laser Excitation of 980 nm, the bright blue emissions of Lu2O3:Yb3+, Tm3+ nanocrystals near 477 and 490 nm were observed due to the (1)G(4)-> H-3(6) transition of Tm3+. The bright green UC emissions of Lu2O3:Er3+ nanocrystals appeared near 540 and 565 nm were observed and assigned to the H-2(11/2)-> I-4(15/2) and S-4(3/2)-> I-4(15/2) transitions, respectively, of Er3+. The ratio of the intensity of green luminescence to that of red luminescence decreases with an increase of concentration of Yb3+ in Lu2O3:Er3+ nanocrystals.
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controllable red green blue rgb and bright white upconversion luminescence of lu2o3 yb3 er3 tm3 nanocrystals through single Laser Excitation at 980 nm
Chemistry: A European Journal, 2009Co-Authors: Jun Yang, Cuimiao Zhang, Chong Peng, Lili Wang, Ruitao Chai, Jun LinAbstract:Light fantastic! Lu(2)O(3):Yb(3+)/Er(3+)/Tm(3+) nanocrystals with controllable red, green, blue (RGB) and bright white upconversion luminescence by a single Laser Excitation of 980 nm have been successfully synthesized (see picture). Due to abundant UC PL colors, it can potentially be used as fluorophores in the field of color displays, back light, UC Lasers, photonics, and biomedicine.Lu(2)O(3):Yb(3+)/Er(3+)/Tm(3+) nanocrystals have been successfully synthesized by a solvothermal process followed by a subsequent heat treatment at 800 degrees C. Powder X-ray diffraction, transmission electron microscopy, upconversion photoluminescence spectra, and kinetic decay were used to characterize the samples. Under single-wavelength diode Laser Excitation of 980 nm, the bright blue emissions of Lu(2)O(3):Yb(3+), Tm(3+) nanocrystals near 477 and 490 nm were observed due to the (1)G(4)-->(3)H(6) transition of Tm(3+). The bright green UC emissions of Lu(2)O(3):Er(3+) nanocrystals appeared near 540 and 565 nm were observed and assigned to the (2)H(11/2)-->(4)I(15/2) and (4)S(3/2)-->(4)I(15/2) transitions, respectively, of Er(3+). The ratio of the intensity of green luminescence to that of red luminescence decreases with an increase of concentration of Yb(3+) in Lu(2)O(3):Er(3+) nanocrystals. In sufficient quantities of Yb(3+) with resprct to Er(3+), the bright red UC emission of Lu(2)O(3):Yb(3+)/Er(3+) centered at 662 nm was predominant, due to the (4)F(9/2)-->(4)I(15/2) transition of Er(3+). Based on the generation of red, green, and blue emissions in the different doped Lu(2)O(3):RE(3+) nanocrystals, it is possible to produce the luminescence with a wide spectrum of colors, including white, by the appropriate doping of Yb(3+), Tm(3+), and Er(3+) in the present Lu(2)O(3) nanocrystals. Namely, Lu(2)O(3):3 %Yb(3+)/0.2 %Tm(3+)/0.4 %Er(3+) nanocrystals show suitable intensities of blue, green, and red (RGB) emission, resulting in the production of perfect and bright white light with CIE-x=0.3456 and CIE-y=0.3179, which is very close to the standard equal energy white light illuminate (x=0.33, y=0.33). Because of abundant luminescent colors from RGB to white in Lu(2)O(3):Yb(3+)/Er(3+)/Tm(3+) nanocrystals under 980 nm Laser diode (LD) Excitation, they can potentially be used as fluorophores in the field of color displays, back light, UC Lasers, photonics, and biomedicine.
